About the Origin of Cities

We provide a bare--bones framework that uncovers the circumstances which lead either to the emergence of equally-spaced and equally-sized central places or to a hierarchy of central places. We show how these patterns reflect the preferences of agents and the efficiency of transportation and communication technologies. Under one class of agents, the economy is characterized by a uniform distribution or by a periodic distribution of central places having the same size. Under two asymmetric classes of agents, the interaction between agents may give rise to a hierarchy of settlements with one or several primate cities.